I think this can be summed up pretty easily.
Remember when Trump said he was was so powerful that he could shoot someone on 5th Avenue, and his popularity wouldn’t suffer?
You may also remember when Trump also said that Hillary could shoot someone at a Trump rally and get away with it. based on how much power she held.
Same act, same result, same cause (both being based on power.) But when HE did it, it was positive. However, when she did the same thing, also based on the same perception of power….it couldn’t possibly be more negative or wrong for America.
Very simply, he can do no wrong. No one else can ever do right.